Method for producing porous nano silica and active carbon by utilizing rice hull ash

Abstract

The invention discloses a method for producing porous nano silica and active carbon by utilizing rice hull ash, which comprises the following steps of: at lower temperature and normal pressure, performing secondary alkali dissolution on subcarbonate, and filtering to obtain alkali-dissolved filter liquor and filter residue; adding a certain amount of dispersing agent into the filter liquor, reducing temperature for ageing, filtering, washing, and removing the dispersing agent to obtain the porous nano silica; and adding an activating agent into the alkali-dissolved filter residue, activating, washing and drying to obtain the high specific surface area active carbon. The alkali and the active carbon can be recycled, and only a small amount of alkali and active carbon is lost. The method has the advantages of not seriously corroding equipment due to no high-temperature and high-pressure alkali boiling, sufficient raw materials, low price, no environmental pollution, and higher quality of the obtained active carbon and silica.

Description

technical field [0001] The invention relates to a method for comprehensive utilization of biological waste resources, in particular to a method for producing porous nano silicon dioxide and activated carbon by using remaining rice husk ash after power generation as raw materials. Background technique [0002] Rice is the crop with the most extensive planting area and the largest yield in the world. At present, the total output of rice in the world is nearly 600 million tons, while the total output of my country is about 200 million tons. Rice husk accounts for about 20% of rice. Although my country's rice husk resources are very rich, the current utilization rate is very low. In rural areas, rice husk is used as livestock feed, but due to its low nutrient content, and the surface of rice husk is densely covered with lignin, which tightly surrounds crude fiber, the total digestibility of livestock intake can only reach 5 %-8%. Therefore, most of the rice husks are discard...

AI Technical Summary

Problems solved by technology

However, this route still has obvious deficiencies: that is, in the process of preparing silicon dioxide, the traditional precipitation method is used to produce white carbon black, which needs to consume a large amount of caustic soda and acid, which not only causes high cost, but also causes Larger environmental pollution, no industrial development value

However, after careful study, it is not difficult to find that on the one hand, this method does not actually achieve the effect of reducing emissions: because the lye needs to be recycled, when a large amount of carbon dioxide is introduced into the solution, the bicarbonate reaches saturation, and in the second cycle , either the bicarbonate is directly decomposed at high temperature, and becomes carbon dioxide again; Reaction formula (1) can find out, and bicarbonate group increases in the lye, then reaction equilibrium carries out to the left, so when reaching equilibrium, the Na in the solution 2 SiO 3 The content of the activated carbon is lower than that of the previous cycle, which leads to a decrease in the output of the second cycle, and the silicon dioxide in the rice husk ash cannot be removed, and the final activated carbon ash content is too high and the quality is low

In addition, because the rice husk is carbonized by direct incineration, most of the bioenergy is wasted; at the same time, it also uses high-temperature and high-pressure alkali boiling to dissolve silica, which seriously corrodes the equipment.

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